Grinding wheel dressing mechanism



June 23, 1959 v w. s. OMWAKE 2,891,534

' GRINDING WHEEL DRESSING MECHANISM Filed Dec. 12, 1956 5 Sheets-Sheet 1 INVENTOR WARREN S. OMWAKE FIG. 3

ATTORNEYS June 23, 1959 w. s. OMWAKE 2,891,534

GRINDING WHEEL DRESSING MECHANISM Filed Dec. 12, 1956 5 Sheets-Sheet 2 INVENTOR WARREN S. OMWAKE BY www ATTORNEYS June 23, 1959 w, s, OMWAKE 2,891,534

GRINDING WHEEL DRESSING MECHANISM Filed Dec. 12, 1956 '5 Sheets-Sheet 5 Wi li an sa s2 62 FIG. 15

INVENTOR WARREN S. OMWAKE A'I'I'ORNEYJ 2,891,534 mo wim'si-nnEssiNo smcnANisM Warre'nS. 'fimwake, Wayne'sboro, Pa;, assignor to" Dandis Mac ine Company, 'Wayneshoro, Pa.,' 'a corporation of Pennsylvania 1 Application December" 12; 1956, Serial No; 6219055 7Claiiiisk mills-=11 This'invention relatesto mechanismsfor dressing grind-:

iug -wheels and morepartioularlytojsuch mechanisms" for generating multiple profiles on grinding'wheels:

Heretofore the operation of dressing a grinding wheelbe formed on the grinding wheel has generally been used when a more complex operation'was involved, such Mechanisms for performing such A mech-- anism including a template duplicating the-contourtoas forming-the profiles of numerous annular ridges -on a wheel-for grinding screw threads. in suchdressing machines a slide carryingthe diamond tool and a template follower traverses both the grinding-wheel-and; the template simultaneously. Such a mechanism is shown, for example, in the United States Patent No 2,447 ,503--issued August 24, 1948 to J. G.-=Harper et a1.

Certain'limitations as to field of use are inherent in the structure of such devices. Relative rectilinearmove rnentbetween the template and follower in a direction parallel to th e grinding wheel axis creates a camming relationship between template and' follower to causethe follower and the attached diamond tool to move in a direction perpendicular to the grinding wheel axis. The surfaces Ion-"the template which cause such movementof the "tool correspond to the flanks of the thread'profile to be' for'med on the grinding wheel. In accordance with wellknow'n cam design principles the flank angle of the threadftha't' is, the angle between the flank of the thread andfaline perpendicular ts the aiiis thereoiwill have a certain m nimum value." If the flank angle is too steep the "aiiial component of the force exertedby the template upon the followerwill be great enough to cause the latter to stick momentarily and to have an irregular and jerky-- radialmovement or no radial mc'ivem entat-all.

Dfespiteithe use of anti-friction bearings to make the" radi'ally i'noving, tool-carrying slide virtuallyfrictionless,-

it isgene'rally recognized that theseconsiderations prohibit'the use of this type of dresser mechanism on trape zoidal, Acme and worm th reads whose flank angles range from" 10 to 20 degrees. Prior attempts -to overcome that limitation have led to the construction of a variety of devices :all of which are extremely complex: ezcpensive,'delicate, slow and subject to error. i i M In the device of the present invention, which overcomes the above-stated disadvantages of prior machines,

the relative rectilinear motion between template: and followeris' a number of times faster than the parallel relative motion between the dressing tool and the grinding Wheel? The differential in traverse velocityi is eifected j by 'a'ratio lever mechanism. The radial inlfeed of the dressing" tool is effected by' the template directly so that the travel of the dressing tool in that directioniseiiactly equ'al'to the depth of the profile formed on the template.

the "direction perpendicular to the 'grindingwh eel axis Thus' while the dimensions of the template profile 1n 2,891,534 Patented tiune23, 1959 The -flank angles-of 'the' thread profile are accordingly increased on'the template; permitting the use of asimple" template-and follower type of-dressing device" to form profiles on 'the-grin'ding wheel whiclr'could'not be'formed'" with prior-mechanisms of comparable cost and simplicity:

According to ;a "further feature "ofrtheinvention,"thei ratiolever mecharlismmay be altered selectively" to obtainvarious magnifications fof the transverse "movement 'be" tween template and followercr to eliminate suchmag nification if desired; a

It is "therefore an object of the inventionto" provide-- a grinding wheel dressing mechan'isrrr-of the templatecontrolled typefor the formation-of profiles having steep flank angles.

Another object "of the invention is to providesuchmechanism having-a slide carrying a'tool and a template Y cap-able of transverse and radial movement relative to" a grinding wheel and of movement in the same direc-; tions relative to the controlling follower or systems, in

which only the transverse relative movement of the'slide I and stylus is magnified with respect' to'the transverse movement the slide relative tOfthB" grinding wheel,

A further object is to-provide mechanism as; above described in which: the transverse movement of the stylus 1 relative to the template is magnified proportionately-by means" of a ratio lever deviceQ A still 'furtherobjecflo'f the invention is to provide mechanism as described above in which the dimensions of the controlling template are magnified with respect'to the grinding whecl'profile in the transverseidirectiononlyl Another object is to provide means for selectively varying 'the "degree of magnification of -th e above-mentioned transverse movement or for eliminating the magnification as desired. I

A further'object otfthe invention is to'provide means? for carrying out the dressing operation automatically with the mechanism described above.

Other": objects "and advantages will be apparent from-T the "following'tdescription of anexempiary embodimentt of the invention and from the accompanying drawings, in which:

Figured is'a front elevation of a grinding wheel dress ing mechanism constructed 'in accordance with the inve i'i l tiongi j Figure 2 lis a side elevation of the mechanism asse'eri from the left hand'sideofFigurel; x i

Figure 3 is a partial'top'planview ofthemechanismg Figure 4 is a verticalsectional'view'taken substantially f along line 4 -4 of Figure 1; 1} Figure 5 is a partial sectional'view taken substantially along line 5-5 of Figure 4, with the stylus, stylus supporting bracket and cover removed; I

Figure 6 is a horizontal sectional view"tak en"suhstan tion of Figure 1, but with certain parts removedfrom the mechanism;

Figure ;10 is a top plan 'view of the parts shown in" ur a Figure ll is a partial section taken'along line 11- 1]; of Figure 1;

Figure 12 is a partial section taken along line 12-12 of Figure Figure 13 is a partial section taken along line" 1313 of Figure 1 and Figure 5;

Figure 14 is a partial section taken along line 1414 of Figure 1;

FigurelSis a partial section taken along line 15--15 of Figure 6; and

Figure 16 is a partial section taken along line 1616 of Figure 15.

As shown in Figures 16 the entire dresser mechanism is mounted on and supported by a base member which may be secured to the bed of a thread grinding machine, for example, in well-known manner. A vertically ar ranged frame 32, generally circular in outline and strengthened by webs 34, is cast integrally with the base member 30. Referring particularly to Figures 4 and 6, the frame 32 is provided with a circular finished surface 36 facing the grinding wheel W. A bracket 38 is held firmly against the surface 36 by means of a headed stud 40 which is journalled through the vertical rear wall of the bracket 38 and the adjacent frame 32, an integral boss 42 being formed on the latter to provide sufiicient bearing area for the stud 40. The rear end of boss 42 is closed by a cap 44 and a cap screw 46 is passed through the cap 44 and threaded into the interior of the stud 40 to retain the parts in position.

The stud 40 serves as a pivot about which the bracket carrying the dressing mechanism may be rotated when the screw 46 is loosened slightly. Thus the entire dressing mechanism may be adjustably tilted so that its movements are aligned with the axis of the grinding Wheel W which is usually inclined to the helix angle of the thread being ground. The axis of the stud 40 should be aligned with the axis about which the grinding wheel is pivoted so that the relative movement between the dressing tool and the grinding wheel will be the same in all angularly adjusted positions thereof. A plurality of plugs 47, backed by springs 48 (Figure 4) may be installed in the boss 42 to press rearwardly against the cap 44 to prevent the bracket 38 from moving away from the surface 36 when the screw 46 is loosened for adjustment and thus prevent foreign matter from entering between the bracket 38 and the surface 36. After angular adjustment and during operation, the screw 46 is tightened and the bracket 38 is stationary relative to the base 30.

A means for accurately adjusting the bracket 38 angularly with respect to the frame 32 is shown in Figures 7 and 8 and includes a pin 50 pressed into the frame 32 and projecting from the rear surface thereof. A second pin 52, spaced angularly from the pin 50, is pressed into bracket 38, extends through an elongated slot 54 in the frame 32 and projects rearwardly therefrom coextensive with the pin 50. An adjusting screw 56 is threadedly engaged in the frame 32, extending into the slot 54 to abut the pin 52 tangentially with respect to the axis of the pivot stud 40. Rotation of the screw 56 will increase or decrease the distance between the pins 50 and 52 and thus finely adjust the bracket 33 angularly, relative to the frame 32. The distance between pins 50 and 52 necessary for any desired angular adjustment may be computed and tabulated in advance and may be measured as by means of micrometers. A coarse adjustment may be indicated by an angular scale 58 (Figure 2) inscribed on the periphery of the frame 32 cooperating with an index mark 60 similarly inscribed on the adjacent periphery of the bracket 38.

A-slide base 62 is secured to the forward surface of the vertical portion of bracket 38 by means of screws 64 and a locating pin 66 (Figure 6). A slide assembly 68 is mounted on base 62 for movement parallel to the axis of the grinding wheel W. The slide 68 comprises a top plate 70 which extends beyond the slide base 62 on all 4 sides. A bottom plate 72, having substantially the same external dimensions as the top plate 70 but having its interior cut away to form a voided rectangle, surrounds the slide base 62. The bottom plate 72 is spaced rearwardly from the top plate 78 and along the sides of the slide base 62 the intervening space is occupied by a pair of bearing strips 74. The assembly is held together by means of screws 75 which pass through top plate 70 and bearing strips 74 and are threaded into the bottom plate 7'2 (Figures 4 and 12). The inwardly directed V-grooves of the strips 74 cooperate with similar outwardly-directed V-grooves formed in the sides of the slide base 62 to form a raceway for a number of bearing rollers 76 (Figures 1S and 16). The rollers 76 are restrained longitudinally by a pair of bearing retainers 78, one of which is disposed on each side of the slide base 62 and between that base and the adjacent bearing strip 74. A pin 80 may be pressed into the center of each bearing retainer 78, projecting on both sides into longitudinal tainers.

As shown in Figure 6, the slide base 62 is cut away as at 84 to accommodate the end portions of the bottom plate 72 in the reciprocal movement of the slide 68. Longitudinally, the top plate 70, bottom plate 72 and bearing strips 74 are of equal extent and are longer than the slide base 62 by an amount equal to the desired length of travel of the slide 68. The ends of the slide 68 are closed by a pair of end covers 86 which are attached to the top and bottom plates by means of screws 88. Protection of the interior of the slide against grinding dust and other foreign matter is obtained by a sealing plate 90 disposed between bottom plate 72 and the adjacent forward surface of the bracket 38. The sealing plate 90 has its central portion voided to surround closely.

the slide base 62 and a plurality of springs 92 (Figure 2) are mounted in bracket 38 to hold the plate 90 tightly against the bottom plate 72. Thus a unitary, dirt-proof and virtually frictionless slide 68 is mounted for sliding movement on the base 62.

Reciprocation of the slide 68 on its base 62 is effected by the following mechanism. A ledge 94 (Figures 4 and 5) is machined in the upper forward portion of the top plate 70 to form a seat for a bracket 96 (Figures 4, 9 and 10) which is secured to top plate 70 by means of screws 98. The bracket 96 projects above top plate 70 and this projecting portion is provided with rack teeth 100 for meshing engagement with a spur pinion 102. The pinion 182. is secured upon a vertically disposed shaft 104 by means of a pin 186. A portion 108 of the bracket 38 projects forwardly above the slide 68 and has a vertical through bore to receive spaced bushings 110 in which the shaft 104 is journalled. A washer 112 is inserted between the hub of pinion 102 and the bracket portion 108, which also comprises an upwardly facing cavity 113 having a boss 114 to support a flange 116, formed integrally on the shaft 104 to maintain the shaft 104 and pinion 102 in correct vertical position.

Above flange 116 the shaft 104 carries a gear 118 and n a pin 120 provides a driving connection between gear 118 and the shaft 104. Meshing with gear 118 and also contained in cavity 113 is a pinion 122 mounted on the output shaft of a geared electric motor 124 (Figures 1 and 2) secured by screws 126 to an extension of the bracket 38. Operation of the motor 124 alternately in the forward and reverse directions will reciprocate the slide 68 on its base 62. The speed of rotation of shaft 104 is reduced from that of the motor both by virtue. of the motors built-in speed reducing mechanism and by the gears 116, 122 which may be replaced with a pair of gears having a different ratio to alter the speed of reciprocation of the slide. The cavity 113 is closed against the entry of dirt as by a cover 128 secured by fasteners. 130 of the well known bayonet type for conssassa venieat aria rapia remevar and replaeemenaer the cover: A pfbtetwehddd 132 is secured to" the radket-portio 108, asbymea'n's of a cam raman-saws i36;to cover the biacket -96 over its entire ldngitudinl'trairl '(Fig uresl, 221mm); A

The alternatingreversal of motor 124 may be effected by'" various means, that ill'ustrated in Figures 2 and-'3 Y beingboth efiicient and-convenient. This nteans comprises an" anglebracket- 138 secured bysorews"l40to the lateral extensionof bracket 68 near the bottom the'ro'f- A pair' of-lirnit switches 142ar'e fastened by" screws144 to the upper surface ofthe bracket 138. The switches 142 1 are =thus disposed-"in a position -to be actuated -'by' a pair of fingers 146 "secured to the upwardly facing surface-of slide 68 "by screws 148. The'fingers 146 trip tlie-switches 142 alternately to operate 'the motor' 124 in the reverse directions- The electrical connections for sue operation are wel-l known and do not require fur-ther 'dischssion.

In {Figure 3 the -fing'e-rs'146 are shown extend-ing rearwardly exactly perpendicular to the path' of travel" of theslide tasx- Itshould be noted that-they may be" set at a 'substanti'al angle relative to the positions shownto thirst/a ry the length oftravel ofthe slide. Alternatively; several hele's may be rovided i in "the bearing strip 74 to reloeate one ofboth *of 'thefingers' 146 to achieve the sarn'e' 'resul-ti As 'be'stsl'lown in' 'Figu're S; a tension" spririgllSlV'is connected between" a spring 5 post 152 screwed into the bot tom plate 72 at"the -'left"eridofslide 68 and asecond' sprir'ig post #154scre'wed' in'td'the bracket 38 near the I righfend thereof The spring-150 thus"'bias'esthe sl'ide 68 'constantly'in onedirection toelim'inate backlash in the-reciprocation tliere'of."-

The bracket 38 is formed 'with'a forwardlyex'tendi-ng'i bottom'portion 156='(Figures 1,14 and 5) havingaaplane horizontal surface 158*011 which a second slidebase'lGiF is mounte'dfi Theslidebase 166 is-attachedtdbracketportion 156 by screws 162"and'a locating .-pin'-164'"(Fig-; ure 5). A slide assembly 166 is mounted" on-base160 in the same mannerasslide'68 is mountedo-n'slide base 62 andfor movement in the same direction. The slide assembly 166com'prises a'topplate 168,- a bottom plate 170' and a pair oftearing strips 1'72, all retained in assembled rela-tion by cap screws174KFigure 4-). Bear ingraces arealSO'provided,along withbea'rin'g rollers 176'"ancfbearingretainers1'78. The structure of slide 166:"

is exactly the sameas that'of'the slide 68 described above and therefore need not'be described further. A'sea'ling Platelet surrounds the"slide base'166 and is pressedupwardly against the bottom plate 170 by springs 182- seated in recesses'in the bracket portion156'and-retained therein by screws 184' (Figure 5).

Asshowh in Figure "5 "the right end of slide "166 is closed byian end cover'plate 1S6 attachedto botlrtop plate 16812.net bottom plate 170 byscrews 188." The left endyhowe'venis closed bya plate 190*extendingm substantial distance above the top plate 168 and attached to top and bottom plates by screws 192- (see"also" Figure 2).

The b'racketportion 156 isformed with a lateral exten-' sion 194 (Figures 1 and 5) which'is bifurcated" (Fig-' ure"s2 and-14) to accommodate'one end'ofa lev'e'r196? Thetwo arms of extension 194 arepierced by 'aligned f The center Y of each' 5 extension 1% parallelto the pins"198"have enlarged heads to engage'a portion ofthe pins 198t0h0ld them in close-contact axially with the bushing -200"(Eigures l and-"14). V

The upperendoflever- 196 -has journalled therein a sms saartizss* Ft ars Sand 2} haviagqn ait gra head-'p'0'rtion2ll8- A pair of renew 210, 212 ar' mounted tor rotati'orin the shaft -206=be'tw'een the h'a'd' f 208and'thelever 1963* A radially directed set screw 214 is thr'eaded through one sideof lever 196-to hold the shaft 2tl6and rollers 210 and 21-2 in axial position? On one side of lever-1% a-block 216'is secured onthe ledge 9 40f the'top 'plat'e itt'of means 68 by means'ofsc'rews' 2181 The block 216 pr'esents a hardened wearsurface 1 220 "for engagement with the "roller: 210, While avoiding 9 contact with the secon'd roller21'2. On tlieotherSid of lever 196, a second block 222 is similarly 'mounted iledge 94 and is securedfio to-p plate '70 'by screws 224.

The block-222 *has'a hardened' sur face' in engagement"- with the roller 212 only. Thus 'there'is-substantiallyino clearance which might permit the" rollers" to move lo'iigttudinally-of-the slide relative to the 'blocks zlt and-222 As shown in FiguresS and-13 a second pair bf -roller' 226"and"228 are rotatably mounted ori th e lever 196 intermediate the ends thereof by-means'of "a-'=stubsha ft The rollers and the shaft are he'ld in' -posi'tion 230. axially-by 1a radially'directed set screw-232 threadedly engaged in one side of the lever'196. A bracket 234' is attached byiscrews 236 to the end plate19tl of-slide- 166 and has a hardened wear' surface 238fo'r engagement byth'e roller 228 (see also Figure'2). The bracket234 extends beyond the lever 196 and a block 24!)"is secured to the end of 'the'bracket 234 by one of the screws 236; presenting a suiface 242 'for'engagement by: the roller 226 on'th'e opposite side of shaft 236 from the surface 238' ing motion of rollers 226 and 228 is translated into recip rocation of the slide 166 by bracket 234and block-240'" which are attached to the slide as described above; The contact surfaces 238 and 242 are beveled as shown at" 244 (Figures 5 and 6) to avoid interfering with the rock ing movement of lever 196' The rectilinear travel of slide 166 in its reciprocatory movement will be proportionately less than that of slide 68 in the ratio of the distance from the center of the shaft 230 to the center of the pivot 198 -209 to the dis tance from the center of the shaft 206 to the same pivot. In the example shown in the drawing the distance from ,the center of the shaft 266 to the pivot is five times the distance from the center of'theshaft 230m the pivot. Thus-thetravel or stroke'of the slide 166 will be -one'-- fifth that of the slide 68.

It is a feature of the invention that this ratiois'maintained accurately throughout the range of movement "of the parts. The hollow bushing 200'and centering :pins- 198 are employed insteadof a conventional-shaft be cause Wearof a unitary shaft would cause the center'of" the pivot opening in lever 1% to-be shifted downwardly? whereas the construction shown permits wear of the bush ing 20% to be compensated for by moving the center pins 198 further inwardly from both ends. Also, the portion of the shaft 239 which carries the 'rollers 226 and 228;

is made slightly eccentric'with respect tothe portion 0f=- the shaft Which is journalled in the lever 196; Thusthe" location of the centers of the rollers can-be-aCc'HrateIyadjusted by rotating the shaft 230. A screw slotmay be provided in the head of the'shaft to facilitate this ad'-- justment.

A pair of tapped holes 246(Figure 2)- is provided in the upward extension of end plate 190. movement ratio is desired; the bracket 234 may be'-re-;

moved from the position shown and relocated upwardly;

thescrews 236 occupying the holes 246. In this posi"- -tion the bracket 234 and the block-240 'coactwifh a If a smaller".

set of rollers 248 and 250 affixed to the lever 196 in the same manner as the other rollers. In the example shown, the center of the stub shaft 252 on which the rollers 248, 250 are mounted is located exactly halfway between the axes of shaft 206 and bushing 200 so that, when these rollers are employed to move the slide 166, the extent of that movement is one-half that of the slide 68.

A third slide base 254 (Figures 4 and 5) is secured on top plate 168 by screws 256 and locating pin 258. The base 254 supports a slide assembly 260 for reciprocating movement in a direction exactly perpendicular to the path of movement of the slide assemblies 68 and 166, that is, perpendicular to the axis of the grinding wheel W. The slide 260 is constructed like the other two slides, having a top plate 262, a bottom plate 264 and a pair of bearing strips 266, all held in assembled relation by screws 268. Bearing races are also provided, along With bearing rollers 270 and bearing retainers 272. A pair of end plates 274, attached to top and bottom plates 262 and 264 by screws 276, close the ends of the slide. A sealing plate 278 surrounds the slide base 254 and is pressed upwardly against the bottom plate 264 by springs 280 seated in recesses in the top plate 168 of slide 166.

As shown in Figure 11, the slide 266 is resiliently biased forwardly by springs 282 seated in recesses in the forward surface of the slide base 254. A headed plug 284 is inserted in the forward end of each spring 282 for engagement by the point of a set screw 286 threaded through the forward side of bottom plate 264.

At the rear end of top plate 262 of slide 266 is formed a ledge 288 whereon a template 2% is secured by means of screws 292 and washers 294- (Figures 5 and 6). The template profile 296 is formed on the forward face thereof for camming engagement with a follower or stylus 298. As shown in Figures 4, 9 and l the stylus 298 is held in a horizontal recess in one side of bracket 96 and is retained therein by a clamp 360, screw 362 and washer 304. It will be noted that in Figure the hood 132, the bracket 96 and associated parts are not shown to illustrate the underlying structure more clearly.

The forward end of top plate 262 is formed with a boss 306 (Figure 2) having a circular opening to receive a tool holder 308. A diamond dressing tool 3110 directed radially toward the grinding wheel W is mounted in a suitable opening 312 in the tool holder 368 and is re tained therein by a set screw 314. The center of the tool 310 which coincides with the center of rotation of the tool holder 308 is aligned with the center of the pivot stud 40. Holder 308 has an integral flange portion 316 which extends a substantial distance to the left of the center of boss 396 as viewed in Figure 6 to lie closely adjacent the forward surface of a similar extension 318 of the boss. The tool holder 3618 can thus be set at various degrees of angular adjustment relative to the extension 318 to which it is secured by a screw 320 and a Washer 322, the screw 320 passing through an elongated slot 324- (Figure I) provided in the flange portion 316. The angular position of the tool holder 368 may be measured by a suitable scale 326 inscribed on the outward edge of the flange portion 316 in cooperation with an index or zero mark 328 on the extension 318.

The angular adjustment just described is provided for the purpose of permitting the diamond tool to present its true profile to the inclined grinding wheel in those cases comprising low helix angles and simple thread outlines where tilting of the entire mechanism about the pivot 40 is unnecessary. It is to be understood that when the mechanism is tilted about the pivot 44), the holder 308 is not pivoted, that is, it is set on zero.

In operation, the motor 124, through gears 122, 116 and 102 and rack 10%), reciprocates the slide 68 in a path parallel to the grinding wheel axis. The reciprocation of slide 68 through blocks 216 and 222 and rollers 21!) and 212 causes the lever 196 to oscillate. The rollers 226 and 228, secured on lever 196 cause reciprocation of the slide 166 in the same direction as slide 68 but at a-, reduced rate of speed and over a reduced path of travel. Consequently, the diamond tool 310, being indirectly v mounted on slide 166 is traversed over the entire operative peripheral surface of the rotating grinding wheel with a rate of speed and length of stroke reduced from those at which the stylus 298, mounted on the slide 68 is traversed relatively to the template 290. The template 2% is kept in camming engagement with the stylus 298- solely by the forward bias given the slide 260 by the springs 282. Thus the relative motion, in the direction of movement of slide 166, between stylus and template causes the slide 260 to be reciprocated transversely, that is perpendicular to the surface of the grinding wheel.

it will be noted that movement of the diamond tool 310 perpendicular to the grinding wheel surface is exactly' equal to the lift of the template 290 in the same direction.

In the example shown, the distance from the center of bushing 200 to the center of shaft 206 is five times the distance from the center of bushing 200 to the center of shaft 230. Therefore, if the length of stroke of slide 68 is said to be five inches, the length of stroke of slide 166 will be one inch. Since the template 290 is indirectly mounted on slide 166, it will move one inch in the same direction. Since the stylus 298 is attached to slide 68 by bracket 96, the stylus will move five inches in the same direction. The resultant relati e movement, then, between stylus 298 and template 290 will be four inches. Thus the profile 296 formed on the template must be expanded laterally at a ratio of 4:1 relative to the profile to be produced on the grinding wheel by the diamond tool 310. Thus, in the example shown, the 14 /2 degree flank angle of the standard Acme thread profile on the grinding wheel becomes approximately 46 degrees on the template 290 which completely eliminates the irregular camming action which would otherwise result in prior template-controlled dressing mechanisms.

As noted above, when the rollers 248 and 250 are used to reciprocate the slide 166, the stroke of that slide will be one-half that of the slide 68 and the resultant relative lateral movement between stylus 298 and template 290 will be exactly equal to the lateral movement of the diamond tool 310. This positioning of the rollers therefore leads to direct correspondence in size between template and wheel in both directions and may be employed in cases where the flank angles are 30 degrees and larger. Other locations may be provided on the lever 196 for the rollers which operate the slide 166 for producing other ratios as desired, provided corresponding holes are formed in the end plate 190 for repositioning the bracket 234.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States Letters Patent is:

1. Apparatus for dressing a grinding wheel mounted on a predetermined axis comprising, a frame, first, second and third slide assemblies, means mounting said first and second slide assemblies in said frame for movement parallel to the axis of said wheel, means mounting said third slide assembly on said second slide assembly for movement normal to the axis of said wheel, a cam element, a follower element, means mounting one of said elements on said first slide assembly and the other of said elements on said third slide assembly, a dressing tool mounted on said third slide assembly, means resiliently urging said third slide assembly toward the periphery of said wheel to urge said tool into engagement with said wheel and maintain said cam and follower elements in contact, a lever pivotally mounted adjacent one end on said frame, means connecting said lever adjacent its opposite end to one of said first and second slide assemblies, means pivotally connecting said lever intermediate its ends to the other of said first and said second slide assemblies whereby when said lever is oscillated about its pivotal axis said first and second slide assemblies are reciprocated, the distance and rate of movement of said one slide assembly being greater than that of the other slide assembly.

2. Apparatus for generating a profile of predetermined depth and width on the periphery of a grinding wheel mounted for rotation about a fixed axis comprising, a frame, first, second, and third slide assemblies, means mounting said first and second slide assemblies in said frame for movement in a direction parallel to said axis, means mounting said third slide assembly on said second slide assembly for movement in a direction normal to said axis, a template mounted on said third slide assembly, said template having a contour of the same depth as said predetermined profile and having a width which is a predetermined multiple of the width of said predetermined profile, a stylus mounted on said first slide assembly opposite said template, means resiliently urging said third slide assembly toward said wheel to urge said tool against the periphery of said wheel and urge said template against said stylus, a lever pivotally mounted adjacent one end on said frame, means pivotally connecting said lever adjacent its opposite end to said first slide assembly, means pivotally connecting said lever intermediate its ends to said second slide assembly, and means to cause said lever to oscillate about its pivotal axis to thereby reciprocate said first and second slide assemblies, the distance between the pivotal connections of said lever to the respective first and second slide assemblies and the pivotal axis of said lever being such that the distance travelled by said first slide assembly is said predetermined multiple of the distance travelled by said second slide assembly.

3. Apparatus for dressing a grinding wheel mounted on a predetermined axis comprising a frame, a bracket mounted on said frame for rotation about an axis lying in a. plane containing the axis of said Wheel, a first slide assembly mounted on said bracket for movement in a direction parallel to said wheel axis and carrying a cam follower, a second slide assembly mounted on said bracket for movement in a direction parallel to said wheel axis, a third slide assembly mounted on said second slide assembly for movement in a direction normal to said wheel axis, a cam and a dressing tool mounted in predetermined relation on said third slide assembly the axis of said tool lying substantially in said plane, means resiliently urging said third slide assembly toward said wheel to urge said cam against said follower and said tool against the periphery of said wheel, and means operative to oscillate said first and second slide assemblies, the distance and rate of movement of said first slide being greater than that of said second slide.

4. Apparatus for dressing a grinding wheel mounted on a predetermined axis comprising a frame, a first slide assembly mounted on said frame for movement in a direction parallel to said axis and carrying a cam follower, a second slide assembly mounted on said frame for movement in a direction parallel to said axis, a third slide assembly mounted on said second slide assembly for movement in a direction normal to said axis, a cam and a dressing tool mounted in predetermined relation on said third slide assembly, means resiliently urging said third slide assembly toward said wheel to urge said cam against said follower and said tool against the periphery of said wheel, a lever pivotally mounted at one end in said frame and engaging said first and second slide assemblies at its opposite end and intermediate its ends, respectively, and a motor operatively connected to oscillate said lever about its pivot axis whereby when said motor is operated said first and second slide assemblies will be oscillated, the distance and rate of movement of said first slide being greater than that of said second slide.

5. Apparatus for dressing a grinding wheel mounted on a predetermined axis comprising a frame, first, second and third slide assemblies, means mounting said first and second slide assemblies on said frame for movement parallel to the axis of said wheel, means mounting said third slide assembly on said second slide assembly for movement normal to the axis of said wheel, a cam element, a follower element, means mounting one of said elements on said first slide assembly and the other of said elements on said third slide assembly, a dressing tool mounted on said third slide assembly, means resiliently urging said third slide assembly toward the periphery of said wheel to urge said tool into engagement with said wheel and maintain said cam and follower elements in contact, a lever assembly pivotally mounted adjacent one end on said frame, pairs of concentric rollers mounted adjacent the opposite end of said lever assembly and intermediate the ends of said lever assembly respectively, means forming wear surfaces on said first and second slide assemblies, respectively, each of said surfaces being adapted to engage one of said rollers, and means for causing said lever assembly to oscillate about its pivotal axis to thereby relatively reciprocate said first and second slide assemblies.

6. The apparatus according to claim 5 together with means for adjusting the position of at least one of said pairs of rollers with respect to the pivotal axis of said lever assembly.

7. The apparatus according to claim 5 wherein at least one of said pairs of rollers is mounted on a pin carried by said lever assembly, the portion of said pin supporting said rollers being eccentric with the portion of the pin carried by the lever assembly whereby rotation of said pin is effective to adjust the distance of the centers of said rollers from the pivotal axis of said lever assembly.

References Cited in the file of this patent UNITED STATES PATENTS 2,184,684 Bickel Dec. 26, 1939 2,706,426 Kelley Apr. 19, 1955 FOREIGN PATENTS 461,223 Great Britain Feb. 12, 1937 

